Programming Fundamentals

#include<iostream.h>
using namespace std;
int main ( )
{
int r;
float p, peri;
r = 2;
p = 3.14;
peri = 2*p*r;
cout<<“Result is = “<<peri<<endl;
return 0;
}
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CS-211 PROGRAMMING
FUNDAMENTALS
Introduction
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C++ (See plus pluss)
To follow syntax and rules of Turbo C++ and Borland
C+
Text editors e.g. WordPad and note pad
These are used to write the code
Compilers are used to run the code
Source code written and stored in first.cpp
Compiled code stored/saved as first.obj
Executed code stored as first.exe
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Contains following three parts
◦ Preprocessor directives
◦ The main( ) Function
◦ C++ statement
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Preprocessor Directives
Instructions given before beginning of actual program
Also called Compiler Directives
To define certain actions or special instructions
(include arithmetic equation)
Normally begin with number sign (#)
May include keywords like “include” or “define”
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Example 1-01
#include<iostream>
int main( )
{
cout <<“this is my first program”;
return 0;
}
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Example 1-01 (output)
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Preprocessor Directives
Header file
C++ source file
Contains definitions of function/objects
“include” is used to add “iostream” into the program
Has Large number of header files in which library
functions are defined
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Example 1-01
#include <iostream>
int main ( )
{
return 0;
}
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Example 1-01
#include<conio.h>
void main( )
{
getch( );
}
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Header file
“iostream” is short of “input output stream”
Has definitions of several input and output objects or
functions
Which was it in the last example?
“cout” (see out)
Syntax
◦ #include <name of the header file>
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Example 1-01
#include<iostream>
int main( )
{
return 0;
}
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The main ( ) Function
Indicates the beginning of a program
After the preprocessor directives
Must be included in every program
Syntax
◦ main ( )
{
program statements…
}
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C++ Statements
Syntax
◦ main ( )
{
program statements…
}
The statements are written under main ( )
Between { }
Are the body of the program
Each statement ends with ‘;’
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C++ Statements
Case sensitivity (must remember)
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C++ Statements
Key words
Words used by languages for
Special purposes
Also called ‘reserved words’
Cannot be used as variable names
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Example 1-02
int main( )
{
int a, b;
}
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C++ Statements
Tokens
Certain elements of a program
Every thing other than a statement
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Example 1-02
main ( )
{
int a, b;
}
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Example 1-03
int main ( )
{
int abc = 4, b = 1997;
float xy = 3.4;
char name[15] = “Marriam Ahmed”;
cout <<name<<endl;
cout<<abc<<endl;
cout<<b<<endl;
cout<<xy<<endl;
return 0;
}
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C++ Statements
Variables
Not a constant
Which may change during execution of a program
Represented by a symbol or a name
Nadeem, fox pro, x, y etc.
It represents a storage location on a computer
Data stored may change, the variable does not
Also known as a object
In C++ variable names consists of alphabets and digits
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C++ Statements
Rules for writing a variable name
First character must be alphabetic, exception ‘_’
No blank spaces
Arithematic characters not allowed #, ^, etc
Reserved words are not allowed
Maximum length depends up on compiler
Must be declared
Again, case sensitive language
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Variables Valid/Invalid Remarks
Nadeem valid
perform valid
double invalid C++ reserved word
foxpro valid
switch invalid C++ reserved word
Marriam valid
int invalid C++ reserved word
3taq invalid Starts with numeral
unsigned invalid C++ reserved word
x-y invalid
Special character is not
allowed
Taq Ahd invalid Space is not allowed
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Each variable (we define) is specified by the data types
of the data stored in it
Each variable is Declared by its type
C++ has 5 basic data types
◦ int Integer 25, 100, 5000
◦ float Floating Point 3.4×105
◦ double double precision 3.4×105
◦ char characters almost all
◦ bool Boolean logic type variables
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The ‘int’ Data Type
Represents the integer type data
Integer is a whole number!
i.e. without fraction or decimal
◦ 601, 250, -6, 501
The range depends the computer system being used
◦ In MS-DOS range is -32768 to 32767
Range can be changed by using following qualifiers
◦ short int
◦ long int
◦ unsigned int
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The ‘float’ Data Type
Represents real or floating type data
Real, decimal or exponential notation
Float, signed or unsigned
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The ‘double’ Data Type
Represents real or floating type data
Twice the storage capacity than ‘float data type’
Long double Data type
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The ‘char’ Data Type
char stands for character
Used to declare character type variables
Variables, alphabetic characters, numeric digits and
special characters can be stored
Twice the storage capacity than ‘float data type’
Long double Data type
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Declaration of Variables
Assigning the name a variable can hold
◦ Zohaib, sum, addition, x, xyz etc
Assigning the data type a variable can hold
◦ int, float etc
Example
◦ int a;
◦ int abc, xyz, d, s;
Can be more than one variables but separated by a
comma (if of same data type)
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Declaration of Variables
If not, written in each individual line where each
statement is ended with a ‘;’
Syntax
◦ type list of variables
Example
int a, xy;
Float b;
Char nm [15]
double sum;
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Initialization of Variables
Before we declared a variable
Declared variable gets a memory location assigned to it
that specifies it has a place in memory on the computer
Now a value to the variable must also be assigned or
defined
A known value is assigned to it
◦ int a = 110
The statement can be written as
◦ int a = 110, b = 60, c;
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Example 1-03
int main ( )
{
int abc = 4, b = 1997;
float xy = 3.4;
char name[15] = “Marriam Ahmed”;
cout <<name<<endl;
cout<<abc<<endl;
cout<<b<<endl;
cout<<xy<<endl;
return 0;
}
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Constants
A value that cannot be changed during execution of a
program
◦ int a = 44
Four types of constants in C++
◦ Integer constants
◦ Floating point constants
◦ Character constants
◦ String constants
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Constants
Integer constants
Numerical value without a decimal part
+ can also be used with it
Integer constants are used in expressions for
calculations
◦ int a = 44, b = 55;
sum = a+b;
cout<<sum<<endl;
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Constants
Floating-point contant
Numeric values having both integer and decimal part
Can also be written in exponential notation
In exponential notation, can be written as
◦ 123.5E2
◦ Where E represents the exponent
both the constant and the E notation can be +
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Example 1-04
#include<iostream>
int main ( )
{
int r;
const float p = 3.14;
float peri;
r = 2;
peri = 2*p*r;
cout<<“Result is = “<<peri;
return 0;
}
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The “define” Directive
It is a preprocessor directive, used at the beginning of
the program
Used to define a constant quantity
Syntax
◦ #define identifier constant
◦ #define p 3.14
Value defined is ‘p’, where 3.14 is the constant
assigned to ‘p’
3.14 remains same throughout the program
‘p’ can not be used again in the program to define other
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The “define” Directive
Identifier does not have any data type but any data type
can be assigned to it
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Example 1-05
#include <iostream>
#define p 3.14
int main ( )
{
int r;
float peri;
r = 2;
peri = 2*p*r;
cout<<“Result is = “<<peri;
return 0;
}
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Arithmetic Operators
Symbols that represent arithmetic operations
Used in arithmetic expressions
Following are the arithmetic operators in C++
Operators Meaning
+ Addition
- Subtraction
* Multiplication
/ Division
% For remainder
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Example 1-06
#include <iostream.h> redundant lines will be excluded
int main ( )
{
int d, p, s, m, r;
p = 5+2;
s = 5-2;
m = 5*2;
d = 5/2;
r = 5%2;
cout<<“Addition of 5 & 2 is =“<<p<<endl;
cout<<“Subtraction of 5 & 2 is =“<<s<<endl;
cout<<“multiplication of 5 & 2 is =“<<m<<endl;
cout<<“division of 5&2 is =“<<d<endl;
cout<<“remainder of 5/2 is =“<<r<<endl;
}
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Arithmetic Expression
It is a combination of variables, constants and
arithmetic operators
◦ p = m*x+100 where m=10 and x=5
Used to calculate value of an arithmetic formula
Returns a single value after evaluation
Here ‘=‘ is called the assignment operator
After evaluation the resultant variable is called the
“receiving variable”
◦ res = m*x+100
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Order of Precedence of Operation
It is the order in which the expression is evaluated
C++ only performs one operation at a time
Following is the order of precedence
◦ All multiplications and divisions are performed first from left
to right
◦ All additions and subtractions are then performed left to right
◦ If parenthesis are used in an expression, the expressions within
parentheses are first computed from left to right
◦ When parentheses are used within parentheses, the expression
within innermost parentheses is evaluated first
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Order of Precedence of Operation
Example (4-(3*5))+2 is evaluated as follows
First?
Solution
◦ (3*5) is computed and returns value of 15.
◦ 4-15 is computed and returns value of -11
◦ -11+2 is computed and returns the value of -9
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Statements used to get some data and assign to
variables are input statements
◦ Int a=10, b=510
Statements used to receive data from computer memory
and send to output devices (monitor) are output
statements
◦ cout<<“your total GPA is = “<<m<<endl;
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The ‘cout’ object –Output Stream
The flow of data from-and-to a device is called a
stream
‘cout’ (see-out) stands for console out
Here the console out is the display screen (monitor)
‘cout’ is used as an output statement and is part of
iostream header file
Example
◦ cout<<“One kilobyte = “<<1024<<“bytes”;
There are two string constants, one numeric constants
and three put to operators
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Example 1-07
#include <iostream.h>
int main ( )
{
cout<<“one kilobyte = “<<1024<<“bytes”;
return 0;
}
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Example 1-08
#include <iostream>
#include <conio> used for functions such as
clearing the screen
int main ( )
{
clrscr ( )
cout<<“C++is a powerful programming language”;
cout<<“UNIX operating system is written in C++”;
cout<<“it is an easy to learn language”;
return 0;
}
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Example 1-09
#include <iostream>
int main ( )
{
cout<<“I ”<<“LOVE ”<<“PAKISTAN” ;
}
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The Escape Sequence
‘endl’ is similar to an escape sequence
Do you remember what it did?
These are special non-printing characters
Used to control printing on the output device
Combination of ‘’ and a code character
For example, n is an escape sequence which is used to
transfer the printing control to a new line
Used inside a string constant or independently
In single or double quotes
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The Escape Sequence
Can be used anywhere in the output stream
for example
◦ cout<<“I Love Pakistann”;
◦ cout<<“I n Love n Pakistan”;
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The Escape Sequence
Escape Sequence Explaination
a sounds an alert or alarm
b
backspace, print sequnce moves
a space back
cout<<"Pakistanb";
cout<<"Punjab";
the ouptput will be
PakistaPunjab
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The “endl” Manipulator
Is an important and most common used manipulator
These are the operators used with put to (<<) operators
Stands for end of line
Has the same effect as “n”
For example
◦ cout<<“C++ n”<<“programming n”<<“language”;
Is equivalent to
◦ Cout<<“C++ “<<endl<<“programming “<<endl<<“language”;
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Example 1-10
#include <iostream>
int main ( )
{
cout<<“I am a ”<<endl<<“Pakistani” ;
return 0;
}
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The “setw” Manipulator
Stands for set width
Used to set width of the output on the output on the
screen
The output is left-justified
Syntax
◦ setw(n) where n is the specified width and is an integer
For example
◦ cout<<setw(10)<<“Pakistan”<<setw(15)<<“Islamabad”;
Is a part of “iomanip.h” header file
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Example 1-11
#include <iostream>
#include<iomanip>
int main ( )
{
cout<<setw(5)<<62<<setw(5)<<8<<endl;
return 0;
}
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Example 1-12 (Assignment Statement)
int main ( )
{
int a, b, c;
a=200;
b=100;
c=a
a=b
b=c
cout<<“value of a = “<<a<<endl;
cout<<“value of b = “<<b<<endl;
}
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Example 1-13
#include <iostream>
int main ( )
{
int year, month;
year = 20;
month = year*12;
cout<<“years = “<<year<<endl;
cout<<“months = “<<month<<endl;
return 0;
}
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The “cin” Object— Input Stream
‘cin’ (see-in) stands for console input
This is an input stream
It is a part of iostream header file
It requires you to input from your keyboard during the execution
of a program
Value is input and press Enter to input the value
Syntax
cin>>var1[>>var2….]; >> is an extraction operator or get
from operator
Usually a separate statement is used for each variable
For example
◦ cin>>a>>b>>c; and press Enter to for typing each data
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Example 1-14
int main ( )
{
int n1, n2, s, p;
cout<<“Enter the first number ? “;
cin>>n1;
cout<<“Enter the second number ? “;
cin>>n2;
s=n1+n2;
p=n1*n2
cout<<“Sum of numbers = “<<s<<endl;
cout<<“Product of numbers = “<<p<<endl;
}
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Example 1-15
#include <iostream>
{
int age;
long int age_mon;
char name[50];
cout<<“Enter the name of the person “;
cin>>name;
cout<<“Enter the age of person in years “;
cin>>age;
age_mon = age*12;
cout<<“Name of the person = “<<name<<endl;
cout<<“Age in months = “<<age_mon<<endl;
}
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Example 1-16
float avg;
char name[20];
int total, cpp, os, edp;
cout<<“Enter the name of the student “;
cin>>name;
cout<<“Enter the marks obtained in C++“;
cin>>cpp;
cout<<“Enter the marks obtained in Operating Systems“;
cin>>os;
cout<<“Enter the marks obtained in EDP“;
cin>>edp;
total = cpp+os+edp;
avg = total/3.0;
cout<<“Name of the student = “<<name<<endl;
cout<<“Total Marks = “<<total<<endl;
cout<<“Average Marks = “<<avg<<endl;
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Example 1-17
{
float c, f;
cout << "Enter the temperature in Fahrenheit? ";
cin>>f;
c=(f-32)*5.0/9.0;
cout<<"The temperature in Celsius is = "<<c<<endl;
return 0;
}
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Example 1-18
{
float r,h,v;
cout << "Enter the radius of the cylinder = ";
cin>>r;
cout << "Enter the height of the cylinder = ";
cin>>h;
v=3.14*r*r*h;
cout<<"The volume of the cylinder is = "<<v;
return 0;
}
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Compound Assignment Statement
We have previously used simple statements, to assign
values to a variable
Like
◦ m=x*100+50
◦ v=p*r*r*h
The same assignment statements can be used to assign
one value to more than one variable.
E.g.
◦ x = y = 16;
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Example 1-19
{
int x, y, a, b, c, s;
x = y = a = b = c = 515;
s = x+y+a+b+c;
cout << "the sum is = " <<s<< endl;
return 0;
}
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Compound Assignment Expression
Is used to add, subtract, multiply etc a value to or from
a variable
◦ Without writing on either side of op ‘=‘
The arithmetic operator is combined with the
assignment operator (=)
Syntax
◦ var op = expression
xy = xy + 10;
◦ Here 10 is added to the variable xy
◦ Where xy already has some value
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Compound Assignment Expression
Which can also be written as
xy + = 10;
Similarly x += 9; is the same as?
◦ x = x + 9;
x -=9; is the same as?
◦ x = x – 9;
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Example 1-20
{
int a,b,c;
a=3;
b=6;
c=9;
c*=(a+b); // c = c * (a+b)
cout << "Result is = " <<c<< endl;
return 0;
}
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Example 1-20 (cout)
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The Comment Statement
Used to show comment on the coding statements in a
program
Used to explain the logic of the program
It is a non-executable statement
◦ // This is a my first program in C++
◦ // Java language is similar to C++
Can be given in any line of the program
e.g.
◦ sum=a+b //used to take sum of two variables
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Example 1-21
{
// declare the variables
int a,c; //a&c are variable names
a=10; //value 10 is assigned to a
c=a*a*a; //assignment statement to calculate cube
/* next statement is the output statement to
print the cube of 10 */
cout << "cube of "<<a <<" = "<<c<< endl;
// this is the end of the program
return 0;
}
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Example 1-21 (cout)
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Programming Fundamentals

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